US20140287299A1 - Heat-Debonding Adhesives - Google Patents

Abstract

A heat-debonding adhesive member is provided. The heat-debonding adhesive member attaches electronic device components such as a battery and a housing together. The heat-debonding adhesive includes a heat-generating layer that generates heat for debonding structures that are attached together using the adhesive member. The heat-generating layer includes a conductive layer that generates heat when a current flows through the conductive layer. The heat-debonding adhesive includes additional adhesive layers such as a voided polymer film having air-filled voids and one or more pressure-sensitive adhesive layers. A debonding tool provides current to conductive contacts on the conductive layer for generating heat in the heat-generating layer when it is desired to debond the structures that are attached together using the adhesive member.

Description

BACKGROUND
• This relates generally to adhesives and, more particularly, to heat-debonding adhesives.
• Adhesives are widely used to attach structures to each other. As an example, electronic devices such as computers and cellular telephones often contain adhesives for mounting components such as batteries and other display components to housing structures, for attaching housing structures to each other, and for otherwise assembling structures within a completed device.
• In some situations, it can be desirable to remove and/or replace an electronic device component that has been attached within the device using adhesive. However, adhesives for attaching electronic device components are typically strong adhesives that are designed to maintain adhesion in a wide range of operating temperatures and operating conditions, including drop events. If care is not taken, adhesive-bonded device components can therefore be damaged or destroyed when removing the components.
• It would therefore be desirable to be able to provide improved adhesives for attaching structures such as electronic device components.
SUMMARY
• An electronic device is provided with structures such as housing structures and electronic device structures associated with electrical components. Adhesives such as heat-debonding adhesives are used to attach these structures to each other.
• The heat-debonding adhesive includes one or more adhesive layers and a heat-generating layer. The heat-generating layer includes conductive material that generates heat for debonding the adhesive. Heat generated in the heat-generating layer reduces the bonding strength of at least one of the adhesive layers.
• The adhesive layers may include pressure sensitive adhesive layers, thermally cured adhesive layers, ultraviolet light curing adhesive layers, or other adhesive layers. The adhesive layers may include adhesive layers that are configured to debond and/or deform at high temperatures such as a voided polymer film. A voided polymer film may be formed from a polymer film having air-filled cavities.
• The air-filled cavities that are located at a surface of the voided polymer film are configured to suction onto a surface of a structure to be bonded or onto other adhesive layers in the adhesive. When heated, the air-filled cavities expand, causing the voided polymer film to warp. The warped film may cause other adhesive layers to debond from a surface.
• The heat-generating layer includes one or more conductive contacts. Currents such as electrically driven currents can be provided to the heat-generating layer through the electrical contacts to induce heating in the heat-generating layer that debonds the adhesive. Magnetically induced currents may also generate heat in the heat-generating layer.
• Further features, their nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a perspective view of an illustrative electronic device such as a laptop computer with structures that are attached to each other with heat-debonding adhesive in accordance with an embodiment.
• FIG. 2 is a perspective view of an illustrative electronic device such as a handheld electronic device with structures that are attached to each other with heat-debonding adhesive in accordance with an embodiment.
• FIG. 3 is a perspective view of an illustrative electronic device such as a tablet computer with structures that are attached to each other with heat-debonding adhesive in accordance with an embodiment.
• FIG. 4 is a perspective view of an illustrative electronic device such as a computer display with structures that are attached to each other with heat-debonding adhesive in accordance with an embodiment.
• FIG. 5 is a perspective view of an illustrative electronic device showing how the device may include heat-debonding adhesive that attaches device components to housing structures and other device components in accordance with an embodiment.
• FIG. 6 is a perspective view of a portion of an illustrative head-debonding adhesive with conductive contacts on a heat-generating layer in accordance with an embodiment.
• FIGS. 7A and 7B are perspective views of a structure that is bonded to a heat-debonding adhesive showing how the heat-debonding adhesive is debonded from the structure in accordance with an embodiment.
• FIG. 8 is a perspective of an illustrative electronic device having a battery that is attached to a housing of the device in accordance with an embodiment.
• FIG. 9 is a perspective of an illustrative electronic device having a display that is attached to a housing of the device in accordance with an embodiment.
• FIG. 10 is a cross-sectional side view of a portion of an illustrative head-debonding adhesive with a heat-debonding layer and a heat-generating layer in accordance with an embodiment.
• FIG. 11 is a cross-sectional side view of a portion of an illustrative head-debonding adhesive with multiple heat-debonding layers and a heat-generating layer in accordance with an embodiment.
• FIG. 12 is a cross-sectional side view of a portion of an illustrative heat-debonding adhesive with conductive contacts formed from openings in a pressure-sensitive adhesive layer and a heat-debonding layer in accordance with an embodiment.
• FIG. 13 is a cross-sectional side view of a portion of an illustrative heat-debonding adhesive with conductive contacts formed from openings in a pressure-sensitive adhesive layer and an insulating layer in accordance with an embodiment.
• FIG. 14 is a cross-sectional side view of a portion of an illustrative heat-debonding adhesive with a heat-debonding layer that extends from an edge of the heat-debonding adhesive in accordance with an embodiment.
• FIG. 15 is a cross-sectional side view of a portion of an illustrative heat-debonding adhesive showing how heat from a heat-generating layer may cause voids in a heat-debonding layer to expand in accordance with an embodiment.
• FIG. 16 is a perspective view of a portion of an illustrative heat-generating layer of a heat-debonding adhesive having conductive traces on a carrier layer in accordance with an embodiment.
• FIG. 17 is a perspective view of a portion of an illustrative heat-generating layer of a heat-debonding adhesive having a conductive sheet on a carrier layer in accordance with an embodiment.
• FIG. 18 is a cross-sectional side view of a portion of an illustrative heat-debonding adhesive having thin wires interposed between a heat-debonding layer and a carrier layer in accordance with an embodiment.
• FIG. 19 is a cross-sectional side view of a portion of an illustrative heat-debonding adhesive having a conductive sheet attached to a thin pressure-sensitive adhesive layer in accordance with an embodiment.
• FIG. 20 is an illustrative diagram showing how a conductive sheet of the type shown inFIG. 19 may be attached to adhesive structures having a heat-debonding layer in accordance with an embodiment.
• FIG. 21 is an illustrative diagram showing how a conductive sheet of the type shown inFIG. 19 may be patterned using a laser in accordance with an embodiment.
• FIG. 22 is a flow chart of illustrative steps involved in attaching structures together using a heat-debonding adhesive in accordance with an embodiment.
• FIG. 23 is a flow chart of illustrative steps involved in debonding structures that are attached together using a heat-debonding adhesive in accordance with an embodiment.
DETAILED DESCRIPTION
• Illustrative electronic devices that have heat-debonding adhesives are shown inFIGS. 1,2,3, and4.
• Electronic device10 ofFIG. 1 has the shape of a laptop computer and hasupper housing12A andlower housing12B with components such askeyboard16 andtouchpad18.Device10 has hinge structures20 (sometimes referred to as a clutch barrel) to allowupper housing12A to rotate indirections22 aboutrotational axis24 relative tolower housing12B.Display14 is mounted inupper housing12A.Upper housing12A, which may sometimes referred to as a display housing or lid, is placed in a closed position by rotatingupper housing12A towardslower housing12B aboutrotational axis24.
• FIG. 2 shows an illustrative configuration forelectronic device10 based on a handheld device such as a cellular telephone, music player, gaming device, navigation unit, or other compact device. In this type of configuration fordevice10,housing12 has opposing front and rear surfaces.Display14 is mounted on a front face ofhousing12.Display14 may have an exterior layer that includes openings for components such asbutton26 andspeaker port28.
• In the example ofFIG. 3,electronic device10 is a tablet computer. Inelectronic device10 ofFIG. 3,housing12 has opposing planar front and rear surfaces.Display14 is mounted on the front surface ofhousing12. As shown inFIG. 3,display14 has an external layer with an opening to accommodatebutton26.
• FIG. 4 shows an illustrative configuration forelectronic device10 in whichdevice10 is a computer display or a computer that has been integrated into a computer display. With this type of arrangement,housing12 fordevice10 is mounted on a support structure such as stand27.Display14 is mounted on a front face ofhousing12.
• The electrical devices ofFIGS. 1,2,3, and4 include heat-debonding adhesives that attach one or more device structures to other device structures or components within the device. The illustrative configurations fordevice10 that are shown inFIGS. 1,2,3, and4 are merely illustrative. In general,electronic device10 may be a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment.
• Housing12 ofdevice10, which is sometimes referred to as a case, is formed of materials such as plastic, glass, ceramics, carbon-fiber composites and other fiber-based composites, metal (e.g., machined aluminum, stainless steel, or other metals), other materials, or a combination of these materials.Device10 may be formed using a unibody construction in which most or all ofhousing12 is formed from a single structural element (e.g., a piece of machined metal or a piece of molded plastic) or may be formed from multiple housing structures (e.g., outer housing structures that have been mounted to internal frame elements or other internal housing structures).
• Display14 may be a touch sensitive display that includes a touch sensor or may be insensitive to touch. Touch sensors fordisplay14 may be formed from an array of capacitive touch sensor electrodes, a resistive touch array, touch sensor structures based on acoustic touch, optical touch, or force-based touch technologies, or other suitable touch sensor components.
• Display14 fordevice10 includes display pixels formed from liquid crystal display (LCD) components or other suitable image pixel structures.
• A display cover layer may cover the surface ofdisplay14 or a display layer such as a color filter layer or other portion of a display may be used as the outermost (or nearly outermost) layer indisplay14. The outermost display layer may be formed from a transparent glass sheet, a clear plastic layer, or other transparent member.
• FIG. 5 is a perspective view of device10 (e.g.,device10 ofFIG. 1,2,3 or4, or any other suitable electronic device) showing how components within the device may be attached to other components, tohousing12, or to display14. In the example ofFIG. 5,device10 includes abattery32 that is attached tohousing12. Heat-debondingadhesive member30 attachesbattery32 tohousing12. Heat-debondingadhesive members30 also attach other components such ascomponents34 withindevice10.Components34 may be electronic components such as printed circuit boards, integrated circuits, a compass, a speaker, a microphone, a vibrator, a structural support member, or any other electronic device components.
• Heat-debondingadhesive members30 may attachcomponents34 tohousing12, to display14, toother components34, or to internal support structures withindevice10.
• FIG. 6 is a perspective view of a portion of a heat-debonding adhesive such as heat debondingadhesive members30 ofFIG. 6. In the example ofFIG. 6, heat-debonding adhesive member30 includes a layer for generating heat such as heat-generatinglayer38.Adhesive member30 also includes additional adhesive layers36.Adhesive member30 may include one or more additionaladhesive layers36 each side of heat-generatinglayer38. Additionaladhesive layers36 may include one or more pressure sensitive adhesive layers, one or more thermo-plastic adhesives, one or more other adhesive layers that are configured to debond and/or deform when exposed to high temperatures, one or more insulating layers, or other suitable adhesive layers.
• Adhesive layers36 may include adhesive layers that maintain adhesive bonds at normal operating temperatures fordevice10 and that debond at relatively high temperatures (e.g., temperatures of over 120 degrees Celsius, temperatures of over 150 degrees Celsius, etc.). As examples, layers36 may include a pressure-sensitive adhesive layer that is softened and/or damaged at relatively high temperatures, a thermo-plastic adhesive that melts at relatively high temperatures, a voided polymer film with air-filled cavities that expand and debond at relatively high temperatures, or other heat-debonding adhesive layers. Heat-generatinglayer38 may include a conductive layer such as a thermally conductive layer or an electrically conductive layer formed on an insulating layer.
• Heat-debondingadhesive member30 ofFIG. 6 includes an extendedportion40 havingconductive contacts42.Conductive contacts42 may be exposed portions of a conductive layer of heat-generatinglayer38. An electrical current may be applied toconductive contacts42. The applied electrical current may generate currents within heat-generatinglayer38 that generate heat within heat-generatinglayer38. The heat generated withinlayer38 may cause a heat-debonding layer oflayers36 to debond from a surface of a structure or may cause other adhesive layers withinlayers36 to warp and/or deform, thereby causing those layers to debond from a surface of a structure.
• FIGS. 7A and 7B show how heat-debonding adhesive member30 may be debonded from a structure to which it is attached by applying a current tocontacts42.
• In the example ofFIG. 7A, a surface of heat-debonding adhesive30 is attached to structure44 (e.g., an electronic device battery such asbattery32, an electronic device housing such ashousing12, an electronic device display such asdisplay14, etc.). Another structure may be attached to an opposing surface of adhesive30, though no additional structure is shown inFIG. 7A for illustrative purposes.
• In the example ofFIG. 7B, a tool such asdebonding tool46 can be used to provide a heat-generating current to heat-generatinglayer38.Debonding tool46 may includeconductive probes50.Probes50 may be configured to deliver a current such as an electrical current to conductive material in heat-generatinglayer38. Heat-generatinglayer38 generates heat in response to the electrical current fromtool46. Heat may be generated inlayer38 through resistive heating, inductive heating, or by transferring heat directly to heat-generating layer by conduction.
• In order to avoid damage to structure44, heat is generated quickly withinadhesive member30 so thatadhesive member30 debonds fromstructure44 before damaging amounts of heat penetrate insulating layers of adhesive member30 (e.g., insulating polymer layers or insulating adhesive layers such as pressure-sensitive adhesive layers).
• The heat generated inlayer38 conductively heats other layers such as adhesive layers36 (seeFIG. 6) ofadhesive member30. The heat that passes intoadhesive layers36 causes adhesive30 to debond fromstructure44. In the example ofFIG. 7B, when a current is supplied tocontacts42, heat that is generated in heat-generatinglayer38 causesadhesive member30 to deform or to warp.
• The deformation ofmember30 generates pulling forces that lift portions ofmember30 at an acute angle with respect to the surface of structure44 (e.g., forces in a direction between the x-y plane and the z-direction ofFIG. 7B). The bonding strength ofadhesive member30 may be stronger in the direction perpendicular to the surface ofstructure44 and in the direction parallel to the surface ofstructure44 than in directions at acute angles with respect to the surface ofstructure44. Pulling forces at an acute angle of pull that are generated by the warping ofmember30 therefore relatively easilydebond member30 fromstructure44 while maintaining the bonding strength ofadhesive30 under normal operation conditions ofdevice10.
• In situations in which adhesive30 is used to attach an electronic device component to an electronic device housing, extendedportion40 ofmember30 may extend from a space between the component and the housing so thatcontacts42 are accessible for debonding ofadhesive30.
• In the example ofFIG. 8,battery32 is attached tohousing12 using a heat-debonding adhesive such asadhesive30.Extended portion40 extends from underneathbattery32 withingap41 betweenbattery32 andhousing12. When it is desired to debondbattery32 fromhousing12, a debonding tool such astool46 is inserted intogap41 so thatprobes50 provide current tocontacts42, thereby debondingbattery32 fromhousing12 without damagingbattery32 orhousing12.
• In the example ofFIG. 9,display14 is attached toledge43 ofhousing12 using heat-debonding adhesive30. In this type of configuration, adhesive30 may extend around some or all of the periphery ofdevice10 onledge43.Extended portion40 extends from betweendisplay14 andhousing12. When it is desired to debonddisplay14 fromhousing12, a debonding tool such astool46 is inserted into a space betweendisplay14 andhousing12 so thatprobes50 provide current tocontacts42, thereby debondingdisplay14 fromhousing12 without damagingdisplay14 orhousing12.
• The examples ofFIGS. 8 and 9 are merely illustrative. In general, heat-debonding adhesive30 may be used to attach any type of structures together and heat that is generated in heat-generatinglayer38 may debond adhesive30 from any type of structure.
• FIG. 10 shows one suitable configuration for heat-debonding adhesive member30. In the example ofFIG. 10, heat-generatinglayer38 includesconductive layer64. Conductive layer may be a thermally conductive layer, an electrically conductive layer, a thermally and electrically conductive layer, etc.Conductive layer64 is formed on an insulating layer such aslayer66.Layer66 may be formed from electrically and/or thermally insulating material such as a polymer material.
• When electrically driven and/or magnetically induced currents flow withinconductive layer64, heat is generated inconductive layer64.
• Conductive layer64 is attached to a heat-debonding adhesive layer such as heat-debonding layer60.
• Heat-debonding layer60 may be formed from a material that holds an adhesive bond at the normal operating temperatures of device10 (e.g., up to 100 degrees Celsius) and that warps and/or debonds at higher temperatures. As examples, heat-debonding layer60 may debond and/or warp at temperatures between 120 C and 150 C, between 120 C and 130 C, between 140 C and 150 C, greater than 120 C, greater than 140 C, or greater than 150 C.
• In one suitable configuration that is sometimes discussed herein as an example, heat-debonding adhesive60 is formed from a voided polymer film. A voided polymer film is a thin polymer sheet having openings such as air bubbles in the polymer sheet. Air bubbles at the surface of the polymer sheet form suction bonds with surfaces that contact the air bubbles. When heat is applied to layer60 (e.g., from layer38) the voids (e.g., the air bubbles) expand, thereby deforming and/ordebonding layer60.
• In the example ofFIG. 10,adhesive member30 includes a first pressure-sensitive adhesive (PSA)layer62 attached to heat-debonding layer60 and a second pressure-sensitive adhesive layer68 attached to insulating/carrier layer66.Adhesive30 may be used to attach structures to each other by pressing a first structure (e.g., a device battery or a device display) againstsurface52 ofPSA62 and pressing a second structure (e.g., a device housing) against opposingsurface54 ofPSA68.
• PSA62 andPSA68 may be configured to bond to a specific type of surface (e.g., the surface of a battery or the surface of an aluminum housing) or may be general pressure-sensitive adhesives that bond to a variety of surfaces.
• Each of PSA layers62 and68 may be configured to form a bond with an attached structure that holds during normal operation of device10 (e.g., at normal operating temperatures fordevice10 such as operating temperatures that occur in a users hand or in a hot car) and during drop events (e.g., when a user drops device10).
• One or both of PSA layers62 and68 may deform as described above in connection withFIG. 7B in response to changes (e.g., deformations or warps) in heat-debonding layer60 when heat is generated in heat-generatinglayer38. In this way, deformations inlayers62 and/or68 may debondadhesive member30 from structures that are attached to surface52 and/orsurface54.
• The layers of adhesive member may each have a characteristic thickness. As examples, pressure-sensitive adhesive layers62 and68 may each have a thickness TP that is between 5 microns and 10 microns, between 9 microns and 11 microns, between 5 microns and 20 microns, greater than 5 microns, less than 15 microns, or less than 10 microns. As examples, heat-debonding layer60 may have a thickness TH that is between 45 microns and 55 microns, between 40 microns and 60 microns, between 30 microns and 85 microns, greater than 30 microns, less than 60 microns, or less than 50 microns. As examples,conductive layer64 may have a thickness TC that is between 5 microns and 10 microns, between 9 microns and 11 microns, between 5 microns and 20 microns, greater than 5 microns, less than 15 microns, or less than 10 microns. As examples, carrier/insulator layer66 may have a thickness TI that is between 5 microns and 10 microns, between 9 microns and 11 microns, between 5 microns and 20 microns, greater than 5 microns, less than 15 microns, or less than 10 microns.
• Thicknesses TP, TH, TC, and TI may be chosen so that the total thickness of adhesive member30 (e.g., the sum of thicknesses TP, TH, TC, and TI) is between 75 microns and 80 microns, between 70 microns and 90 microns, less than 100 microns, less than 90 microns, less than 80 microns, or less than 75 microns (as examples).
• The configuration ofadhesive member30 ofFIG. 10 is merely illustrative. Other configurations may be used.
• In the example ofFIG. 11,adhesive member30 is provided with an additional heat-debonding layer60′. Heat-debonding layer60′ is attached to carrier/insulator layer66 of heat-generatinglayer38. When heat is generated inconductive layer64 oflayer38, changes (e.g., expanding voids in a polymer film) inlayers60 and60′ cause warping ofPSA layer62 and68 that debondadhesive member30 from structures that are bonded tosurfaces52 and/or54.
• FIG. 12 is a cross-sectional view of a part ofextended portion40 ofadhesive member30 showing howcontacts42 may be formed from an opening in pressure-sensitive adhesive layer62 and heat-debonding layer60. Openings such asopening70 expose part ofconductive layer64 to formcontacts42.Probes50 of tool46 (seeFIG. 7B) may be inserted into openings such asopening70 in order supply a current toconductive layer64.
• FIG. 13 is a cross-sectional view of a part ofextended portion40 ofadhesive member30 showing howcontacts42 may be formed from an opening in pressure-sensitive adhesive layer68 and insulating/carrier layer66. Openings such asopening73 expose part ofconductive layer64 to formcontacts42.Probes50 of tool46 (seeFIG. 7B) may be inserted into openings such asopening73 in order supply a current toconductive layer64.
• The configurations ofextended portion40 shown inFIGS. 12 and 13 are merely illustrative. If desired,extended portion40 may be formed from a portion of heat-generatinglayer38 that extends from an edge ofadhesive member30 as shown inFIG. 14. In the example ofFIG. 14, layers66 and64 of heat-generatinglayer38 extend beyondedge65 of adhesive member30 (e.g., an edge formed from aligned edges oflayers62,60 and68). Anextended portion40 of this type may run along some or all ofedge65 ofmember30. If desired,member30 may be provided with multipleextended portions40 along multiple edges.
• FIG. 15 is a cross-sectional view of a portion ofadhesive member30 showing how heat-debonding layer60 may be formed from a voided polymer film. In the example ofFIG. 15,layer60 is formed from polymer material61 (e.g., a polymer blend, a polymer alloy, or other polymer material) withvoids72.Voids72 are air-filled cavities or cavities filled with other gasses withinmaterial61.Voids72 have a characteristic thickness T. Thickness T may be between 1 mm and 3 mm, between 0.5 mm and 5 mm, between 0.1 mm and 0.9 mm, smaller than 1 mm, smaller than 3 mm, larger than 0.01 mm or between 1 mm and 5 mm (as examples).
• Voids72S that are formed at the outer surfaces oflayer60 may adhere to a material that contacts those outer surfaces by suctioning onto the material.
• As shown inFIG. 15, whenheat74 from a conductive element such aselement79 ofconductive layer64 enterslayer60, some or all ofvoids72 expand (as indicated by arrows76). This expansion of voids72 (and72S) in response to heat74 may warp, debond, or even destroylayer60. The warping oflayer60 causes other adhesive layers such as PSA layers62 and/or68 to warp and or bend as described in connection withFIG. 7B, thereby debonding PSA layers62 and/or68 from a surface to which they are bonded.
• FIG. 16 is a perspective view of a portion of heat-generatinglayer38 showing howconductive layer64 may be formed from metal traces78 on carrier/insulator layer66.Traces78 may be formed from conductive material such as copper or aluminum. In the example ofFIG. 16, traces78 are etched metal traces that form a meandering path onlayer66. Resistance to current flowing throughtraces78 generates heat that passes into one or more adhesive layers such as a heat-debonding layer ofadhesive member30. However, the meandering traces ofFIG. 16 are merely illustrative. If desired,conductive layer64 may be formed in other configurations such as in a continuous conductive sheet as shown inFIG. 17.
• In the example ofFIG. 17,conductive layer64 is a continuous sheet of conductive material (e.g., metal, copper, aluminum, or other suitable conductive material) that covers substantially all oflayer66. In this type of configuration, heat can be generated inlayer64, for example, by inducing eddy currents within sheet64 (e.g., by applying magnetic fields to sheet64). A conductive sheet of the type shown inFIG. 17 may have a thickness that is less than the thickness oftraces78 ofFIG. 16. For example the thickness ofsheet64 ofFIG. 17 may be between 3 microns and 7 microns, between 1 microns and 10 microns, less than 10 microns, less than 7 microns, or less than 5 microns (as examples).
• FIG. 18 is a cross-sectional view of a portion ofadhesive member30 showing howconductive layer64 of heat-generatinglayer38 may be formed fromthin wires80 that run between carrier/insulator layer66 and heat-debonding layer60.Wires80 are coupled to contacts42 (see, e.g.,FIG. 7A) so that currents that pass throughwires80 generateheat74 that passes into one or more heat-debonding layers. In this type of configuration,layer66 may holdwires80 in place against heat-debonding layer60.
• In some configurations, heat-generatinglayer38 may be formed from a conductive layer such as a thin conductive foil that is provided without an insulating carrier layer as shown inFIG. 19.
• In the example ofFIG. 19,conductive foil84 is formed from a thin conductive sheet having a thickness TCS.Conductive foil84 is interposed between pressure-sensitive adhesive layer62 and an additional pressure-sensitive adhesive layer86.Conductive foil84 may be formed from metal such as copper or aluminum.Layer86 may have a thickness TP2 that is smaller than thickness TP oflayers62 and/or68 so that heat generated infoil84 can pass throughlayer86 into heat-debonding layer60. Thickness TCS ofconductive foil84 may be, as examples, between 3 microns and 7 microns, between 1 micron and 10 microns, less than 10 microns, less than 7 microns, or less than 5 microns. Thickness TP2 oflayer86 may be, as examples, between 4 microns and 7 microns, between 3 microns and 10 microns, less than 10 microns, less than 7 microns, or less than 5 microns.
• FIG. 20 is a diagram showing howadhesive member30 ofFIG. 19 may be formed from a firstadhesive component90 and a secondadhesive component92. In the example ofFIG. 20,component90 includes pressure sensitiveadhesive layer62 attached toconductive foil84.Component92 includes heat-debonding layer60. Pressure-sensitive adhesive layer68 is attached to one side of heat-debonding layer60 and thin pressure-sensitive adhesive layer86 is attached to an opposing side oflayer60.
• If desired,member90 may be manufactured separately frommember90. In this type of situation,member90 is attached tomember92 as indicated byarrow94 to form a heat-debonding adhesive member such as heat-debonding adhesive member30 ofFIG. 19. By pressingconductive foil84 againstlayer86,member90 is bonded tomember92.
• If desired,conductive foil84 may be a patterned conductive foil layer.Foil84 may be etched or otherwise patterned before being attached tomember92 or after attachment tomember92. For example, as shown inFIG. 21, laser light may be used to etch a pattern intofoil84. In the example ofFIG. 21,laser99 generateslaser light97.Laser light97 has a wavelength that is chosen so that laser light97 passes throughPSA layer62 and is absorbed byfoil84 so that patterned structures such asopening88 are formed infoil84. Openings such asopening88 may pass completely or partially throughfoil84 and may form any desired pattern infoil84.Patterned openings88 infoil84 may enhance the heat that is generated infoil84 when currents are applied to foil84 (e.g., through conductive contacts such ascontacts42 ofFIG. 6).
• Illustrative steps that may be used in attaching structures together using a heat-debonding adhesive member such as heat-debonding adhesive member30 are shown inFIG. 22.
• Atstep100, a first structure to be attached (bonded) is provided. The first structure may be an electronic device structure such as a housing, a battery, a printed circuit board, a display, another electronic device structure or any other suitable structure.
• Atstep102, a second structure to be attached (bonded) to the first structure is provided. The first structure may be an electronic device structure such as a housing, a battery, a printed circuit board, a display, another electronic device structure or any other suitable structure.
• Atstep104, an adhesive member such as a heat-debonding adhesive member having a heat-generating layer and first and second pressure-sensitive adhesive layers is provided. The provided adhesive member may include additional layers such as a heat-debonding layer of the type that is included in heat-debonding adhesive member30 ofFIGS. 5,6,7A,8,9,10,11,12,13,14,15,16,17,18,19,21 (as examples).
• Atstep106, the first structure is attached (bonded) to the second structure by pressing the first structure against the first pressure-sensitive adhesive layer and pressing the second structure against the second pressure-sensitive adhesive layer.
• If it is desired to detach the first structure from the second structure, atoptional step108, the first structure is detached (debonded) from the second structure by generating heat using the heat-generating layer of the provided adhesive member. The heat may be generated by applying or inducing a current in a conductive layer of the heat-generating layer. The generated heat may cause changes in a heat-debonding layer of the adhesive member that detach the adhesive member from one or both of the first and second structures. For example, the generated heat may expand air bubbles in a voided polymer layer that cause the adhesive member to deform and debond from the structures.
• Illustrative steps that may be used in detaching structures that are bonded together with a heat-debonding adhesive member such as heat-debonding adhesive member30 are shown inFIG. 23.
• Atstep110, first and second structures that are bonded together by a heat-debonding adhesive member such as heat-debonding adhesive member30 (e.g., an adhesive member having a heat-generating layer and a heat-debonding layer) are provided.
• Atstep112, a tool such asdebonding tool46 ofFIG. 7B is applied to contacts such asconductive contacts42 on the heat-generating layer of the adhesive member.
• Atstep114, heat is generated within the adhesive member with the heat-generating layer. For example, currents may be generated (e.g., electrically driven or magnetically induced currents) in the heat generating layer using the applied tool. The currents generate heat in a conductive material in the heat-generating layer.
• Atstep116, the first structure is debonded from the second structure using the heat that is generated in the heat-generating layer. The generated heat may cause changes in the heat-debonding layer of the adhesive member that detach the adhesive member from one or both of the first and second structures. For example, the generated heat may expand air bubbles in a voided polymer layer that cause the adhesive member to deform and debond from the structures.
• The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Claims (26)

What is claimed is:

1. An adhesive member, comprising:

at least one adhesive layer having a bonding strength; and

a heat-generating layer attached to the at least one adhesive layer, wherein the heat-generating layer is configured to generate heat that reduces the bonding strength of the at least one adhesive layer.

2. The adhesive member defined inclaim 1 wherein the at least one adhesive layer comprises a voided polymer film.

3. The adhesive member defined inclaim 2 wherein the at least one adhesive layer further comprises a pressure-sensitive adhesive layer attached to the voided polymer film.

4. The adhesive member defined inclaim 3 wherein the at least one adhesive layer further comprises an additional pressure-sensitive adhesive layer attached to the heat-generating layer.

5. The adhesive member defined inclaim 2 wherein the at least one adhesive layer further comprises an additional voided polymer film attached to the heat-generating layer.

6. The adhesive member defined inclaim 2 wherein the heat-generating layer comprises:

a carrier layer; and

a conductive layer formed on the carrier layer.

7. The adhesive member defined inclaim 6 wherein the conductive layer comprises patterned conductive traces on the carrier layer.

8. The adhesive member defined inclaim 6 wherein the conductive layer comprises a sheet of conductive material on the carrier layer.

9. The adhesive member defined inclaim 6, further comprising an extended portion having conductive contacts.

10. The adhesive member defined inclaim 6 wherein the conductive layer comprises metal wires interposed between the carrier layer and the voided polymer film.

11. An electronic device, comprising:

a first device structure;

a second device structure; and

a heat-debonding adhesive that attaches the first device structure to the second device structure, wherein the heat-debonding adhesive includes at least one heat-generating layer.

12. The electronic device defined inclaim 11 wherein the heat-debonding adhesive includes a heat-debonding adhesive layer attached to the at least one heat-generating layer.

13. The electronic device defined inclaim 12 wherein the first device structure comprises a battery.

14. The electronic device defined inclaim 13 wherein the second device structure comprises a housing.

15. The electronic device defined inclaim 14 wherein the heat-debonding adhesive includes an extended portion having conductive contacts.

16. The electronic device defined inclaim 15, further comprising a gap between a portion of the housing and the battery, wherein the extended portion of the heat-debonding adhesive extends into the gap.

17. The electronic device defined inclaim 12 wherein the first device structure comprises a display and wherein the second device structure comprises a housing.

18. A method of debonding a first structure from a second structure, wherein the first structure is bonded to the second structure with a heat-debonding adhesive member that is interposed between the first structure and the second structure, comprising:

generating heat within the heat-debonding adhesive member using a heat-generating layer of the heat-debonding adhesive member; and

debonding the first structure from the second structure using the generated heat.

19. The method defined inclaim 18 wherein the heat-generating layer includes a conductive layer and wherein generating the heat within the heat-debonding adhesive member using the heat-generating layer of the heat-debonding adhesive member comprises generating a current in the conductive layer.

20. The method defined inclaim 19 wherein generating the current in the conductive layer comprises applying a debonding tool to conductive contacts on the conductive layer.

21. The method defined inclaim 18 wherein debonding the first structure from the second structure using the generated heat comprises expanding air-filled cavities in a voided polymer film in the heat-debonding adhesive member.

22. The method defined inclaim 21 wherein the heat-debonding adhesive member includes a pressure-sensitive adhesive layer attached to the voided polymer film and wherein debonding the first structure from the second structure using the generated heat further comprises deforming the pressure-sensitive adhesive layer with the voided polymer film.

23. A method of attaching a first structure to a second structure, comprising:

providing the first structure;

providing the second structure;

providing an adhesive having a conductive layer and first and second pressure-sensitive adhesive layers;

pressing the first structure against the first pressure-sensitive adhesive layer; and

pressing the second structure against the second pressure-sensitive adhesive layer.

24. The method defined inclaim 23 wherein the adhesive further comprises a voided polymer film attached to the first pressure-sensitive adhesive layer and wherein pressing the first structure against the first pressure-sensitive adhesive layer comprises pressing the first structure against the first pressure-sensitive adhesive layer that is attached to the voided polymer film.

25. The method defined inclaim 24 wherein the first structure comprises a battery and wherein pressing the first structure against the first pressure-sensitive adhesive layer comprises attaching the adhesive to the battery.

26. The method defined inclaim 25 wherein the second structure comprises an electronic device housing structure and wherein pressing the second structure against the second pressure-sensitive adhesive layer comprises attaching the battery to the electronic device housing structure using the adhesive.

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